- Jan 24, 2023

What is a scant quarter-inch seam allowance and why should I use it?

If you’re a quilter, you’ve probably heard the term “scant quarter-inch seam allowance” thrown around. But what exactly is it? A scant quarter-inch seam allowance is when your seam allowance measures slightly less than a quarter-inch. It’s a common technique used by quilters when piecing. Let’s take a closer look at what it is, why, and how you should use this technique in your next project.

What is a scant quarter-inch seam allowance?

Ironically, a “scant” means slightly less than an exact measurement—in sewing, slightly less than 1/4 inch (about 1/8 - 3/16 inch). So you may be asking, well, Ledine, if I need to sew at a scant 1/4,” but it’s not exact, how am I supposed to know where to sew?! That is the elusive issue! I wondered this for so long until I finally found an answer that made sense.

Essentially, we want to aim for one thread length away from 1/4 inch, or the width taken up by the seam itself – fabric and thread. This is why a scant 1/4-inch seam matters! Let’s talk about this a bit more…

Rhetorical question…have you ever followed a pattern exactly, and your blocks weren’t the size they were supposed to be? Or the seams didn’t line up, even though you did everything you were supposed to? Of course, you have; I’m sure we all have. If you think about it, we use different fabrics and threads, which take up room in our seams. So what we THINK is an accurate 1/4 inch seam may not be one at all.

Why Use a Scant Quarter-Inch Seam Allowance?

Now that we know what a scant ¼ inch seam allowance is, you may be wondering why it matters and when you should we use it. Don’t worry—we’re here to break it down for you and explain why it’s so important. Because of the nature of patchwork, accuracy is essential! If your seams are too wide, the finished block will be too large, and if they’re too narrow, it will be smaller than it should be. A scant quarter-inch seam allowance ensures that your blocks are as close to the correct size as possible by accounting for the space of fabric and thread, thus yielding a more accurate seam.

Here are a few other considerations for you:

What type of fabric are you using, and is it on the thicker side? What about your thread? Is it a bit thicker? How will you press your seams? If pressing to one side, this can take up more room within the blocks. If you are pressing open, then the seams are more open. Also, take a look at your pattern. If there are a lot of seams, then there are more opportunities for those small “smidges” to add up.

How To Achieve a Scant Quarter-Inch Seam Allowance

If you already have a method to ensure a quarter-inch seam, then you simply need to account for one thread length narrower. If you use a specialty presser foot, then measure off this foot. If you use tape or a guide on your machine, then move this over to account for the scant. Some sewing machines will allow you to move the needle position over one position.

If you don’t have confidence in your seam allowance, check out my blog article on how to achieve the perfect quarter-inch seam allowance. Again, whichever method you use to set yourself up, adjust slightly narrower for the scant quarter-inch.

There is a great guide that I found that actually measures a scant for you-the Sew Very Smooth Ideal Seam Gauge. You simply put your needle down in the appropriate space and then use a magnetic guide or tape. This is the only brand that I’ve seen that shows a scant!

How do you feel about scant quarter-inch seam allowances now?

Scant quarter-inch seams are an essential part of quilt making, as they help ensure accuracy in all your projects! Understanding what a scant quarter-inch seam allowance is and why it’s important can help make all the difference in giving your quilts that perfect professional finish! So next time you start working on any sort of quilting or sewing project where accuracy matters, don’t forget about this handy tip—a little extra effort goes a long way in creating something truly special! So if you haven’t already tried using this technique in your quilts, make sure to give it a shot--you may just find it makes all the difference in helping you create beautiful projects!

Products I recommend for perfect seams:

Magnetic Seam Guide

Ideal Seam Guide

Diagonal Seam Tape

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